Late Quaternary paleoecology from fossil beetle communities in the Awatere Valley, South Island, New Zealand

Aim The research aim is to reconstruct last glacial maximum (LGM) and Holocene vegetation history and ecology from fossil beetle assemblages. Location The LGM and Holocene sites are located in the Awatere Valley, which lies in the tectonically active Marlborough Region in the north east of the South Island of New Zealand. Methods Beetle fossils were extracted from silty organic sediment using the standard kerosene flotation method. Fossils were identified by comparisons made to modern species based on morphology and surface features. The ecology and distribution of modern analogues are extrapolated to reconstruct the fossil environment. Results One hundred and forty‐five beetle species belonging to 33 families were identified. The LGM fossil fauna showed the local vegetation was characterized by a forest patch surrounded by an open tussock/grassland landscape. This Nothofagus (southern beech) forest persisted at the site until mid‐Holocene when it was replaced by a podocarp forest that contained high beetle diversity. Herbivores dominate in the early stage of this zone, indicating a relatively new forest environment. Later in the Holocene, the fauna is dominated by detritivores indicating an older more established forest. The late Holocene is characterized by low diversity and the absence of forest species. This fauna indicates that by 500 years ago, the forest was absent and is associated with an almost compete loss of beetle biodiversity. Main conclusions The fossil beetles provide a unique perspective into the past environment in the Awatere Valley on a local scale. The reconstruction supports regional pollen interpretations of Holocene vegetation by identifying a specific forest patch. Fossil beetles are thus a valuable local proxy for vegetation reconstructions.     

Genetic structure of the common impala (Aepyceros melampus melampus) in South Africa: phylogeography and implications for conservation

We analysed 131 common impala (Aepyceros melampus melampus) samples from two provinces in South Africa (Limpopo and KwaZulu‐Natal) that are separated by the Drakensberg Mountain Range using sequences of the mitochondrial control region and seven polymorphic nuclear microsatellite loci. In line with earlier studies on bovid species, we found very high values of genetic diversity, particularly at the mtDNA locus with an overall nucleotide diversity of 3.6% and an overall haplotype diversity of 0.98. All statistical approaches confirmed a significant population differentiation between Limpopo and KwaZulu‐Natal, suggesting that areas of unsuitable habitat caused by the presence of the Drakensberg Range and the Indian Ocean coastal belt act as a barrier to gene flow. Only few individuals with signs of admixed origin were indicative of translocations or rare migration between the two provinces. Combination of our mtDNA data set with those of previous studies on impala from south‐western, southern and eastern Africa revealed the highest diversity in South Africa. This is in line with the hypothesis of a southern glacial refuge from which various African ungulate species spread northeast during the Holocene, although in the case of impala further analyses based on larger data sets will be necessary to definitively settle this question.     

Diversity of rodent and shrew assemblages in different vegetation types of the savannah biome in South Africa: no evidence for nested subsets or competition

Identifying nonrandom species composition patterns predicted by assembly rules has been a central theme in community ecology. Few studies have investigated the prevalence of multiple drivers on species composition patterns in small mammal assemblages in the Old World. This study investigated seasonal changes in rodent and shrew diversity in eleven savannah vegetation types in South Africa. We tested whether species composition patterns are nonrandom with respect to predictions from Diamond's assembly rules, niche limitation hypothesis and nestedness hypothesis. Species richness estimators indicated that inventories for the rodents (80%) and shrews (100%) were relatively complete. Rodent (n = 11 species) diversity and shrew (n = 5 species) diversity were highest in summer and lowest in autumn. Rodent richness was highest in the Terminalia sericea bushveld and woodlands and lowest in the Drypetes arguta sand forest, whilst shrew richness was highest in the T. sericea bushveld and woodlands and lowest in the Acacia nilotica/Dichrostachys cinerea open shrub savannah. We found no support for the predictions of competition and nestedness hypotheses and suggest that this was probably due to the high seasonal and annual variability in rodent and shrew diversity.     

Nitrogen nutrition,carbon accumulation and δ13C of Cyclopia and Aspalathus species in different settings of the Cape fynbos,South Africa

Aims Cyclopia and Aspalathus are legumes harvested for production of Honeybush and Rooibos tea, respectively. Farmers grow these species from either seeds or cuttings over several years with continuous annual harvesting. The aims of this study were to assess the effect of plant age, plant species, toposequence, planting material and farmer practice on nitrogen (N) nutrition and water-use efficiency of two Cyclopia and Aspalathus species in the Cape fynbos.Methods The study was conducted using plants from Koksrivier farm located near Gansbaai (33° S 18° E, 39 m.a.s.l), and at Kanetberg farm near Barrydale (33° S 21° E, 830 m.a.s.l). The 15 N natural abundance technique was used to determine N 2 fixation, carbon (C) assimilation and δ 13 C in shoot of Cyclopia and Aspalathus species.Important findings Older tea plantations of C. genistoides and C. subternata derived more N from fixation and exhibited greater water-use efficiency than younger plants. At Koksrivier, Aspalathus caledonensis and A. aspalathoides showed greater water-use efficiency and derived more N from fixation than Cyclopia genistoides. Annual harvesting of C. genistoides decreased N 2 fixation. At Kanetberg, C. subternata plants on the upper and middle slopes derived more N from atmospheric fixation than those on the lower slope. C. subternata plants grown from seedlings recorded greater %Ndfa than cuttings. N 2 fixation and water-use efficiency of Cyclopia was affected by age, slope and planting material. Further, symbiotic N nutrition and water-use efficiency of Cyclopia and Aspalathus were related.     

Physiological responses to folivory and phytopathogens in a riparian tree,Brabejum stellatifolium,native to the fynbos biome of South Africa

The canopies of many tree species sustain a large diversity of folivorous arthropods and phytopathogenic fungi. These organisms are thought to influence overall tree and stand productivity. Leaf diseases caused by Phyllosticta owaniana and Periconiella velutina, phytopathogenic fungi commonly found on the native riparian tree Brabejum stellatifolium (wild almond), like any other leaf disease, can potentially reduce a plant's photosynthetic efficiency. In addition to these two phytopathogens, the weevils Setapion provinciale and Setapion quantillum are abundant in wild almond canopies. Despite their pervasive occurrence, the impacts of these phytopathogens and arthropods on host tree leaf physiology have not been examined. The gas exchange response of wild almond leaves to phytopathogens and folivore damage was assessed. Leaf nitrogen, phosphorus and water content were also determined. Declines in photosynthetic rates and other physiological parameters were associated with increasing damage severity by weevils and phytopathogens in leaves of B. stellatifolium. Nitrogen and phosphorus contents were negatively associated with disease severity. Water and phosphorus contents were also negatively correlated with increased weevil damage, while nitrogen content was positively correlated with it. The observed responses of B. stellatifolium metabolic functioning to fungal pathogen and folivory indicate a possibility of suppressed wild populations of wild almond.     

Influence of rainfall seasonality on African lowland vegetation during the Late Quaternary: pollen evidence from Lake Masoko, Tanzania

Aim  To determine if changes in the key bioclimatic parameters associated with rainfall seasonality can be quantified from fossil sequences and to distinguish them from changes in the total annual rainfall.
Location  Lake Masoko, southern Tanzania (9°20' S, 33°45' E, 840 m a.s.l.).
Methods  Fossil pollen was extracted from a long and well-dated sedimentary sequence spanning the period 45,000–4400 cal. yr bp . The modern habitat, geographical distribution and climatic range (mean annual rainfall and temperature, and length of the dry season) of selected East African plants were used to infer past rainfall attributes for the most characteristic fossil pollen taxa identified from the sediments of Lake Masoko.
Results  In the Masoko pollen sequence it has been possible to identify changes in the length/severity of the dry season during the last 45,000 cal. yr bp , which are interpreted to reflect shifts in the mean position of the Intertropical Convergence Zone (ITCZ) over the southern tropics. We suggest that this bioclimatic parameter has been the main driver of the vegetation dynamics in this area. The major inferred change occurred at the Younger Dryas–Holocene transition c . 11,800 cal. yr bp , when semi-deciduous forest disappeared, being replaced in the lake catchment by woodland, which persists to the present day in spite of locally high rainfall.
Main conclusions  In tropical regions under the influence of the ITCZ, the position and strength of which determine the distribution of rainfall through the year, more attention must be paid to the impact of the length and intensity of the dry season on the modern and past distribution and dynamics of the vegetation. This climatic parameter is as important as the total annual amount of rainfall, and probably one of the most relevant in lowland areas.     

Identifying spatial components of ecological and evolutionary processes for regional conservation planning in the Cape Floristic Region, South Africa

Abstract. Conservation seeks ultimately to protect and maintain biodiversity indefinitely. Most biodiversity features targeted in past conservation planning have been largely aspects of ecological and biogeographical pattern rather than process. However, the persistence of biodiversity can only be ensured through consideration of the ecological and evolutionary processes that underpin biodiversity, as well as its present spatial pattern. This paper identifies spatial surrogates of ecological and evolutionary processes for regional conservation planning in one of the world's biodiversity hotspots, the Cape Floristic Region. We identified six types of spatial components (namely edaphic interfaces, upland–lowland interfaces, sand movement corridors, riverine corridors, upland–lowland gradients and macroclimatic gradients) as surrogates for key processes such as ecological and geographical diversification, and species migration. Spatial components were identified in a GIS using published data and expert knowledge. Options for achieving targets for process components have been seriously compromised by habitat transformation. Between 30 and 75% of the original extent of the spatial components currently remain functional. Options for achieving upland–lowland and macroclimatic gradients are very limited in the lowlands where most of the habitat has been transformed by agriculture. We recommend that future studies place their research on ecological and evolutionary processes in a spatially explicit framework. Areas maintaining adaptive diversification (e.g. environmental gradients, ecotones) or containing historically isolated populations should be identified and protected. The spatial dimensions of eco-logical processes such as drought and fire refugia also need to be determined and such insights incorporated in conservation planning. Finally, connectivity within these areas should be ensured to maintain species migration and gene flow.     

Vertebrate assemblages from the north‐central Main Karoo Basin,South Africa,and their implications for mid‐Permian biogeography

The rich fossil vertebrate record from the Beaufort Group, Main Karoo Basin, provides a global standard for mid‐Permian to Mid‐Triassic continental faunas. However, recent studies have demonstrated variability in the composition of contemporaneous faunas across Gondwana. This raises the question of how much the vertebrate faunas differ within the Karoo, where the taxonomic composition of vertebrate assemblage zones (AZs) is mostly considered to be uniform. Although fossil material is known from across the outcrop of the Beaufort Group, the lowest Beaufort strata have received little attention, particularly north of S31°10′. Here, we report two fossil tetrapod assemblages from the lowest Beaufort Group in the southern Free State Province, which represent the northernmost point at which the lowest Beaufort has been targeted for collecting. The lower assemblage is characterized by an abundance of the small dicynodont Eosimops and can thus be attributed to the Tapinocephalus AZ (Guadalupian), but the absence of dinocephalian or pareiasaurian material is unlike contemporaneous assemblages found further south. This suggests that the Tapinocephalus AZ was not uniform across the entire basin and highlights that the abundance, distribution and taxonomic composition of Karoo biozones may vary more than currently appreciated. The upper assemblage, characterized by the dicynodonts Oudenodon, Aulacephalodon and Dinanomodon, is attributable to the upper Cistecephalus AZ to lower Daptocephalus AZ. The juxtaposition of the lower Tapinocephalus AZ and upper Cistecephalus\lower Daptocephalus AZ in the southern Free State implies a stratigraphic gap from the Middle to Late Permian of up to 6 million years.     

Taphonomic and paleoecological change in the large mammal sequence from Boomplaas Cave,western Cape,South Africa

Excavations conducted by H.J. Deacon in the 1970s at Boomplaas Cave (BPA) uncovered a stratified sequence of Middle Stone Age (MSA) and Later Stone Age (LSA) deposits spanning the last >65,000 years. This study provides the first comprehensive and integrated taphonomic and paleoecological analysis of the BPA large mammals, with a focus on its implications for understanding human adaptations and environmental changes in southern Africa's Cape Floristic Region (CFR), an area that features prominently in understanding modern human origins. Taphonomic data indicate a complex history of human, carnivore, and raptor accumulation of the large mammal assemblage. The anthropogenic signal is largely absent from the bottom of the sequence (>65,000 years ago), intermediate in MSA and LSA assemblages from ∼50,000 to 20,000 years ago, and strong in LSA deposits post-dating the Last Glacial Maximum (LGM). When viewed in the broader CFR context, the inferred occupation history of BPA is consistent with the hypothesis that both MSA and LSA human populations were concentrated on the submerged coastline from ∼60,000 to ∼20,000 years ago. Intensive occupation following the LGM parallels an apparent increase in regional population densities, which may have been driven in part by rising sea levels. The BPA ungulate assemblage is characterized by the rise and decline of a taxonomically diverse grazing community, which peaks during the LGM. These changes are not correlated with taphonomic shifts, meaning that they are likely driven by environmental factors, namely the expansion and contraction of grassland habitats. Changes in ungulate diversity indicate that effective precipitation was highest during the LGM, corresponding with an intensified winter rainfall system. This is consistent with recent arguments that the LGM in this region may not have been extremely harsh and arid.     

Late Quaternary vegetation and climate change in the Panama Basin: Palynological evidence from marine cores ODP 677B and TR 163-38

The Late Quaternary paleoenvironmental history from Pacific slopes of the western Andes is reconstructed by pollen analysis of 32 samples from two marine sediment cores from the Panama Basin, eastern equatorial Pacific: core ODP 677B (83°44.2200′ W, 1°12.1440′ N, 3473 m water depth) is 185 cm long and spans the last 39,410 years, core TR 163-38 (81.583° W, 1.337° N, 2200 m water depth) is 103 cm long and covers the last 17,380 years. Six ecological groups were established: mangrove, brackish and fresh water swamps, terra firma lowland forests, broad range taxa, Andean forests, and open vegetation. A good correspondence was found between the changes of these ecological groups in the two cores. The records evidence the continuous presence of all vegetation types during the last 39,410 years and specially the uninterrupted occurrence of tropical rain forest. They record a development from: (1) a cold and humid phase (39,410-28,120 yr cal BP) with moderately high sea levels, (2) the coldest and driest phase in the record (28,120-14,500 yr cal BP) accompanied by the lowest sea levels, (3) a transitional phase when sea level rose and humid conditions dominated, (4) a stage (11,300-5600 yr cal BP) of the highest sea levels and moisture conditions including a drier period ∼7000 yr BP, to (5) a final period (5600 yr cal BP-Present) when sea level reached its present height, humidity persisted, and indicators of disturbance expanded. Peaks in pollen and spore concentration, associated with high river discharge periods, indicate periods of higher precipitation around 33,500, 28,000 and 12,000-9000 yr cal BP. Although main vegetation responses seem to reflect rainfall and moisture variations, a good correspondence was found between δ¹⁸O values and percentages of Andean and lowland pollen, suggesting that vegetation also responded to tempearture changes.     

Impact of land use on vegetation composition, diversity, and selected soil properties of wetlands in the southern Drakensberg mountains, South Africa

Wetlands provide the ecosystem services of enhancing water quality, attenuating floods, sequestrating carbon and supporting biodiversity. In southern Africa, the pattern and intensity of land use is influenced by whether land tenure is public (state), private (individual ownership), or communal (shared agricultural and grazing resources). The influence of land tenure and its associated use on service provision was compared for communal tenure (grazing, maize production), wildlife conservation, and commercial agriculture (grazing, planted pastures) in the southern Drakensberg. Ordination analyses revealed that oxbow marshes, hill slope seepages and hygrophilous grasslands, the main hydro-geomorphic units, supported distinct plant communities that differed in their response to land use because of wetness or slope. Oxbows, uncultivated because of wetness, were inherently species poor with few exotics. Composition of hill slope seepages, uncultivated because of saturated slopes, varied among tenure types most likely in relation to grazing pressure. Seepages were threatened by the exotic invasive Rubus cuneifolius. Eighty-five percent of hygrophilous grassland had been cultivated by 1953, most of which was subsequently abandoned to secondary grassland. Primary hygrophilous grassland and hill slope seepages were the main repository for indigenous plant diversity, while communal maize fields supported a diverse mixture of mainly exotic species. Soil carbon concentrations decreased from oxbows to pastures, seepages, primary hygrophilous grassland, secondary grassland, and maize on former grassland (7.0, 4.1, 4.0, 3.5, 2.4, and 1.7%, respectively). The pattern for total soil nitrogen and sulphur were the same. Cultivation of hygrophilous grassland was estimated to have reduced soil carbon stocks to 69% of pre-settlement levels by 1953 (∼150 years BP). Stocks then increased by 8% to 2001 following crop abandonment. Cultivation has impaired water quality enhancement and flood attenuation because of greater amounts of bare ground and shorter vegetation. Further improvement of ecosystem services will depend on the influence of socio-economic factors on communal cropping.     

Late Quaternary paleoproductivity and deep water circulation in the eastern South Atlantic Ocean: Evidence from benthic foraminifera

Two late Quaternary sediment cores from the northern Cape Basin in the eastern South Atlantic Ocean were analyzed for their benthic foraminiferal content and benthic stable carbon isotope composition. The locations of the cores were selected such that both of them presently are bathed by North Atlantic Deep Water (NADW) and past changes in deep water circulation should be recorded simultaneously at both locations. However, the areas are different in terms of primary production. One core was recovered from the nutrient-depleted Walvis Ridge area, whereas the other one is from the continental slope just below the coastal upwelling mixing area where present day organic matter fluxes are shown to be moderately high. Recent data served as the basis for the interpretation of the late Quaternary faunal fluctuations and the paleoceanographic reconstruction.

During the last 450,000 years, NADW flux into the eastern South Atlantic Ocean has been restricted to interglacial periods, with the strongest dominance of a NADW-driven deep water circulation during interglacial stages 1, 9 and 11. At the continental margin, high productivity faunas and very low epibenthic δ¹³C values indicate enhanced fluxes of organic matter during glacial periods. This can be attributed to a glacial increase and lateral extension of coastal upwelling. The long term glacial-interglacial paleoproductivity cycles are superimposed by high-frequency variations with a period of about 23,000 yr. Enhanced productivity in surface waters above the Walvis Ridge, far from the coast, is indicated during glacial stages 8, 10 and 12. During these periods, cold, nutrient-rich filaments from the mixing area were probably driven as far as to the southeastern flank of the Walvis Ridge.     

城市化地区河岸带植被特征及其与河岸硬度的关系——以晋江市为例

确立了滨河河道硬度与滨河土地硬度两个指标,用以研究城市化地区河岸带的植物构成、多样性与均匀度、优势植物等特征与河岸硬度的关系。选定晋江市都市区12条主要河流作为研究对象,通过样地调查收集数据,并采用相应指数进行数据处理分析,结果表明:(1)调查河流的河岸带植被物种共计70科143属159种,其中乔木20科30属41种,灌木15科15属20种,草本35科98属98种,草本居主导地位,河流间种类分布不均衡;(2)河岸带植物乔灌草区系均以广义热带性成分居多,其次为世界性成分、温带性成分,无中国特有分布类型,乔木中广义热带成分占绝对主导,直观反映地带性特征,灌木与草本中的温带成分多于乔木中的温带成分,类型趋于多元,种类更丰富;(3)从河岸植被优势植物构成来看,主要优势乔木与灌木基本为本土植物,而主要草本中外来植物入侵严重,对地带性植物景观的指示显然不及乔木与灌木;(4)从河岸植被的人工美学属性来看,灌木优势植物中园林观赏植物的种类数显著多于乔木、草本优势植物,反映出晋江人工审美主导的滨河景观空间主要改变与塑造了灌木层植被景观;(5)从河岸植物的人居需求属性来看,龙眼、杨桃等多见于庭院林、水岸林的水果树种也在河岸植被中频繁出现,反映出人口密集区由于对植物生产用途的重视而对河岸植被产生的影响;(6)滨河土地硬度与河道硬度对河岸带灌木植物的影响最强烈,二者均对河岸带植物多样性造成威胁,且前者具有更大的影响力,而后者直接影响了河岸植物的分布形态,出于生产与审美目的的人为干扰对河岸带植物优势种的影响力随滨河硬度的增加而加强,低滨河硬度有助留存原生植被群落;(7)天然弯曲的河流形态对河流植被特征具有积极影响,有助于保留更多本土植被类型,并能在某种程度上丰富乔灌草的植物种类,但这种缓和作用无法根本扭转河岸硬化对植物多样性的胁迫影响。研究表明,城市化地区河流的岸带植被特征与沿线人为干扰类型和强度密切相关,恢复与塑造河岸生态景观要以乡土植被为主,通过乔木景观塑造地带性景观,并以灌木与草本丰富植被景观。     

The implications of Tertiary and Quaternary sea level rise events for avian distribution patterns in the lowlands of northern South America

Aim To assess the correspondence between current avian distributions in the lowlands of northern South America with respect to the hypothesized importance of sea level rise and other events over the past 15 million years on speciation. Location Tropical lowlands of north‐western South America. Methods To establish which bird taxa may have originated in each area of endemism, I examined the ranges of all bird species occurring in the Pacific and the Caribbean lowlands. To determine land and sea distribution during a sea level rise of 100 m in north‐western South America and eastern Central America, I traced the 100 m contour line from the Geoatlas of Georama and the Global 30‐Arc‐Second Elevation Data (GTOPO30) produced by the US Geological Survey. Results During a sea level rise of ～100 m, marine incursions would have occurred from the Caribbean Sea and the Pacific Ocean. Several areas of tropical forest and dry/arid vegetation would have been isolated, currently known as the Darién, Chocó, Nechí, Catatumbo, Tumbesian and Guajiran areas of animal and plant endemism. Main conclusions A large part of the high diversity of forest and nonforest birds and other animals and plants in the Pacific rain forest and the Caribbean woodland likely arose as the result of sea level rises, dispersal and other geological and climatic events.     

Nitrogen and phosphorus limitation in a coastal barrier salt marsh: the implications for vegetation succession

1 A factorial fertilizer experiment was conducted in a 15-year-old coastal barrier salt marsh with a low soil nitrogen content, and in an older 100-year-old marsh with a higher nitrogen content. Plots were fertilized at high and low marsh elevations in both marshes. Nitrogen and phosphorus were applied at low and high concentrations both separately and in combination in each of 3 successive years.
2 Nitrogen limited above-ground plant growth in both young and old salt marshes in all years. Phosphorus limitation of plant growth was apparent in the first year in the young marsh and in the last year in both marshes. In young marshes with low soil organic matter, phosphorus limitation may occur. In addition, phosphorus limitation occurs at both successional stages when a marsh is saturated with nitrogen.
3 Plant species that are typical of nitrogen-rich habitats and late successional stages significantly increased in biomass after fertilization. Limonium vulgare , a low stature species of early and intermediate successional stages, decreased in biomass, whereas the taller Elymus pycnanthus and Artemisia maritima increased. After 3 years of fertilization, plant species composition in a young marsh was similar to the species composition in an unfertilized older marsh. Fertilization of a 100-year-old marsh, however, still resulted in a change in plant species composition, suggesting that succession was still occurring and that, overall, plants in marshes of different age are similar in their response to fertilization.     

Rangewide phylogeography in the greater horseshoe bat inferred from microsatellites: implications for population history, taxonomy and conservation

The distribution of genetic variability across a species' range can provide valuable insights into colonization history. To assess the relative importance of European and Asian refugia in shaping current levels of genetic variation in the greater horseshoe bats, we applied a microsatellite-based approach to data collected from 56 localities ranging from the UK to Japan. A decline in allelic richness from west Asia to the UK and analyses of F(ST) both imply a northwestward colonization across Europe. However, sharp discontinuities in gene frequencies within Europe and between the Balkans and west Asia (Syria/Russia) are consistent with suture zones following expansion from multiple refugia, and a lack of recent gene flow from Asia Minor. Together, these results suggest European populations originated from west Asia in the ancient past, and experienced a more recent range expansion since the Last Glacial Maximum. Current populations in central Europe appear to originate from the Balkans and those from west Europe from either Iberia and/or Italy. Comparisons of R(ST )and F(ST) suggest that stepwise mutation has contributed to differentiation between island and continental populations (France/UK and China/Japan) and also among distant samples. However, pairwise R(ST) values between distant populations appear to be unreliable, probably due to size homoplasy. Our findings also highlight two priorities for conservation. First, stronger genetic subdivision within the UK than across 4000 km of continental Eurasia is most likely the result of population fragmentation and highlights the need to maintain gene flow in this species. Second, deep splits within China and between Europe and China are indicative of cryptic taxonomic divisions which need further investigation.     

Natural regeneration potential of abandoned agricultural land in the southern Gadarif Region,Sudan: implications for conservation

The present study seeks to provide a contribution to the understanding of vegetation regrowth on abandoned agricultural land by investigating the impacts of the previous cultivation period and the duration of the fallow on the subsequent natural regeneration in terms of vegetation composition, structure and diversity. The results of the study show that both factors have significant effects on the subsequent regeneration of plant species and thus the vegetation development in the southern Gadarif Region, Sudan. The oldest abandoned farmlands were recolonized by tree/shrub species, whereas recently abandoned ones are covered with herbaceous vegetation. There is a general tendency regarding the number of species to decrease with an increase in the period of cultivation. The plant species diversity pattern shows domination of herbaceous species with some scattered woody species. Vegetation changes due to land abandonment may have implications for the conservation of plant species diversity and composition of fauna harboured in the region. Although natural regeneration could be recommended as means of restoring natural vegetation that previously dominated that region, the current regeneration capacity might not be sufficient to reach the climax vegetation except for some pockets, which received more regenerative resources.     

Taxonomy of the proterosuchid archosauriforms (Diapsida: Archosauromorpha) from the earliest Triassic of South Africa,and implications for the early archosauriform radiation

Proterosuchidae is one of the first clades of Archosauriformes (archosaurs and closely related species) to appear in the fossil record, with the richest sample of the group coming from the Lystrosaurus Assemblage Zone (earliest Triassic) of South Africa. Four nominal proterosuchid species were described from South Africa during the twentieth century (Proterosuchus fergusi, Chasmatosaurus vanhoepeni, Chasmatosaurus alexanderi and Elaphrosuchus rubidgei), but interpretations of their taxonomy have been widely disparate. The most recent taxonomic revision concluded that P. fergusi is the only valid species and that the other nominal species are junior subjective synonyms of this taxon. This proposal was based on the interpretation that anatomical differences between the nominal species could be explained as a result of ontogenetic changes and/or post‐mortem deformation. The recent discoveries of multiple new South African proterosuchid specimens provide an impetus to revisit their taxonomy. Based upon a comprehensive re‐examination of all known specimens, as well as examination of other proterosuchid taxa in collections worldwide, we conclude that the holotype of Proterosuchus fergusi is undiagnostic. As a result, we propose a neotype (RC 846) for the species. ‘Chasmatosaurus vanhoepeni’ and ‘Elaphrosuchus rubidgei’ are considered subjective junior synonyms of P. fergusi. ‘Chasmatosaurus’ alexanderi is considered a valid species, for which we propose the new combination P. alexanderi comb. nov. A third species, P. goweri sp. nov., is erected on the basis of a single specimen (NMQR 880). All three species recognized here are taxonomically distinct from a previously described archosauriform maxilla from the lower Lystrosaurus AZ. As a result, we recognize a minimum of four archosauriform species following the Permo‐Triassic mass extinction in South Africa. Our results suggest a greater species richness of earliest Triassic archosauriforms than previously appreciated, but that archosauriform morphological disparity remained low and did not expand until the late Early Triassic – early Mid‐Triassic.     

Trend,signal and noise in the ecology of Ostracoda: information from rare species in low-diversity assemblages

Samples of Ostracoda from nearshore marine environments, where the water is more likely to be brackish or hypersaline, typically have low species diversity and are dominated by such species as Cyprideis torosa. In high-diversity samples from normal-marine environments, rare species are likely to contribute to environmental noise. Evaluation of low-diversity samples from Lake Manzala, Egypt, however, shows that the environmental signal provided by rare species can be masked by the overwhelmingly dominant species, C. torosa. In such instances, the dominant species should be removed from the data set and studies based on a large sample of the rare species.